DEVELOPMENT OF ATRIAL CHAMBER OF AMPHIOXUS. 449 

 are here reproduced (Figs. 1 aud 2), bear this description out, 

 Fig. 1. Fig. 2. 



Copy of Kowalevskj's figures of transverse sections through a larva of Am- 

 phioxus with fully formed atrium. Fig. 1 represents a section taken 

 between pharynx and atriopore; and Fig. 2, one taken just behind the 

 atriopore of the same larva. Int. Intestine, at. Atrium, l.h. Ccelom. 



more or less, while Rolph's schematic figures bear it out 

 entirely. The latter are reproduced in Figs. 3, 4, and 5. 



Fig. 3. 



r-Lh 



Copy of Rolph's theoretical section through the pharyngeal region of a larva 

 before the formation of the so-called epipleural folds. N . Nerve-cord. 

 M. Muscles. D. Intestine, b. Epidermis. Ch. Notochord. Lh. Ccelom. 

 a. Intestinal epithelium. 



The most serious error in Kowalevsky's view lies in the fact 

 that he makes the space in the lateral outgrowths continuous 



